Jeju Volcanic Island & Lava Tubes Republic of Korea
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JEJU VOLCANIC ISLAND & LAVA TUBES REPUBLIC OF KOREA The island is an inactive shield volcano where successive eruptions on its flanks have formed 120 large lava tubes and 360 parasitic cinder and scoria cones all over the island, and a large cliff-like cone of tuff offshore. The tubes contain a variety of both lava and carbonate speleothems, some formed, unusually, by secondary carbonates leached from overlying sands. The mountain summit has endemic relic alpine flora. Threat to the site: Development of a major naval base on the island. COUNTRY Republic of Korea NAME Jeju Volcanic Island & Lava Tubes NATURAL WORLD HERITAGE SERIAL SITE 2006: Inscribed on the World Heritage List under Natural Criteria vii and viii. STATEMENT OF OUTSTANDING UNIVERSAL VALUE The UNESCO World Heritage Committee issued the following statement at the time of inscription: Jeju Volcanic Island and Lava Tubes is a coherent serial property comprising three components. The unequalled quality of the Geomunoreum lava tube system and the exhibition of diverse and accessible volcanic features in the other two components demonstrate a distinctive and important contribution to the understanding of global volcanism. Criterion (vii): The Geomunoreum lava tube system, which is regarded as the finest such cave system in the world, has an outstanding visual impact even for those experienced with such phenomena. It displays the unique spectacle of multi-coloured carbonate decorations adorning the roofs and floors, and dark-coloured lava walls, partially covered by a mural of carbonate deposits. The fortress-like Seongsan Ilchulbong tuff cone, with its walls rising out of the ocean, is a dramatic landscape feature, and Mount Halla, with its array of textures and colours through the changing seasons, waterfalls, display of multi-shaped rock formations and columnar-jointed cliffs, and the towering summit with its lake-filled crater, further adds to the scenic and aesthetic appeal. Criterion (viii): Jeju has a distinctive value as one of the few large shield volcanoes in the world built over a hot spot on a stationary continental crust plate. It is distinguished by the Geomunoreum lava tube system, which is the most impressive and significant series of protected lava tube caves in the world and includes a spectacular array of secondary carbonate speleothems (stalactites and other decorations), with an abundance and diversity unknown elsewhere within a lava cave. The Seongsan Ilchulbong tuff cone has exceptional exposures of its structural and sedimentological characteristics, making it a world-class location for understanding Surtseyan-type volcanic eruptions. The property is well managed and resourced, with a management plan in place for the period 2006-2010 and resources for its implementation. Key management issues include avoiding potential agricultural impact on the underground environment and managing the high number of visitors to the property. There is potential for further extension of the property to include other significant lava tube systems and volcanic features of Jeju. 1 INTERNATIONAL DESIGNATION 2002: Centre of Jeju Island designated a Biosphere Reserve under the UNESCO Man & Biosphere Programme (83,094 ha). IUCN MANAGEMENT CATEGORY Hallasan National Park: IV Habitat/Species Management Area Mount Halla National Park: V Protected Landscape BIOGEOGRAPHICAL PROVINCE Japanese Evergreen Forest (2.2.2) GEOGRAPHICAL LOCATION Jeju Island lies 80 km south of the Korean mainland between the East China Sea and the Korea Strait, centred on 33o21’31”N by 126 o32’31”E. DATES AND HISTORY OF ESTABLISHMENT 1962: Manjanggul and Gimnyeonggul Lava Tubes registered as Natural Monuments under the Cultural Properties Protection Act; 1966: Hallasan designated a Natural Monument (9,093 ha); 1970: Hallasan designated a National Park (14,900 ha) under the National Parks Act; 1996: Dangcheomuldonggul Lava Tube declared a Natural Monument; 1997: Hallasan, Ilchulbong Tuff Cone and Bengdwigul Lava Tube declared Absolute Preserved Areas; Ilchulbong declared a County Park; 2000: Ilchulbong Tuff Cone declared a Natural Monument; 2002: Central Jeju designated a UNESCO Biosphere Reserve; 2005: Geomunoreum Volcanic Cone declared a Natural Monument; 2006: Yongcheondonggul Lava Tube declared a Natural Monument. LAND TENURE Hallasan National Park is almost 100% state owned; Geomunoreum Lava Tube System is 48.4% owned by Jeju Province, 51.6% privately owned; and Ilchulbong Tuff Cone is 60% owned by the state and 40% by the Province. The nominated site as a whole is to be supervised by the Jeju World Natural Heritage Management Committee under the Cultural Heritage Administration through the Jeju Provincial Government, but each site is separately managed. AREA Core zone: 9,475.3 ha. The buffer zone of 9,370.8 ha is not designated. Subsite Core zone Buffer zone Hallasan Natural Reserve 33 o19´04´´- 33 o25´38´´N by 126 o32´15´´- 126 o38´08´´E 9,093.17 ha 7,347.4 ha Geomunoreum Lava Tube System 33 o26´27´´- 33 o33´48´´N by 126 o42´54´´- 126 o47´33´´E 330.3 ha 1,906.4 ha Seongsan Ilchulbong Tuff Cone 33 o27´05´´- 33 o28´09´´N by 126 o55´56´´- 126 o57´03´´E 51.8 ha 117.0 ha ALTITUDE Sea level to 1,950m (Hallasan/Mt. Halla) PHYSICAL FEATURES Jeju Island, an oval some 73 km long by 32 km wide, is the low crest of a dormant shield volcano, rising some 3,000m from the ocean bed, formed by an eruption from a magmatic plume under a stationary tectonic plate. Hallasan, the main dome in the middle of the island, is surrounded by a plateau and lava 2 plains spattered with 368 parasitic cinder and scoria cones formed by fountains of lava, 46 in Hallasan Park alone, and by 120 radial lava flows resulting from small eruptions on the flanks of the shield. Many of the flows, densest on the north and west, run in underground tubes resulting from the channelled eruptions of molten lava. The summit of the mountain is a trachyte dome flanked with columnar jointing, with a shallow grassed crater 550m across, holding a lake. Halfway down, the hillside is peopled with tall trachyte pillars (‘the 500 disciples of Buddha’), the eroded remnants of dykes. Elsewhere there are basaltic tuff cliffs and even avian and hominid fossil footprints. The mountain soils are shallow . The lava flows were formed over a period of 1.2 million years, of fine-grained basalt in the form of great tubes of rock where the outer shell of the flow solidified and a highly fluid pahoehoe lava characteristic of shield volcanoes drained out, leaving a long broken cave-like void in its centre, often with walls deeply striated by lava marks along the line of flow. One of these is nominated, the exceptional 13 km- long Geomunoreum Lava Tube System, formed 300,000-100,000 years ago, and comprising a scoria cone and 8 large lava tubes along one segmented line of flow to the sea. The tubes contain a great variety of lava and carbonate speleothems, the latter more often found in limestone caverns: stalactites and stalagmites both massive and delicate, curtains, helictites and soda straws, lava drops and long round rolls, flowers of calcite and rock pearls. At the seaward end, biogenic minerals leached from overlying sand dunes have seeped in to form striking carbonate formations on the walls: such secondary mineralisation is very unusual. Many of these processes are ongoing. Jeju contains almost every possible type of phreatomagmatic vulcanism, notably, at the eastern end of the island, a large headland cone of tuff (fine ejected fragments) formed 120,000-40,000 years ago, which rises castle-like 179m above the sea, in a circle of cliffs eroded almost to the summit crater. This is Seongsan Ilchulbong Tuff Cone, also nominated, resulting from a Surtseyan type of submarine magmatic explosion which, where eroded, exposes in a clear section through nine layers of tuff the eruptional history of the crater. The island is a natural text-book for the study of volcanoclastic sedimentology and volcanic tube caves. In this list characterising the main tube-caves of the Geomunoreum system, only Manjang is partly open to the public. The last two were only discovered in the last decade, so many more may yet be found. Name Length Characteristics Bengdwi 4,481m Most labyrinthine tube, passages on three-levels, composite lava flows, speleothems: stalagmites, chambers, bridges, pillars. Manjang 7,416 m Two-story cave, to 23 m in width and 18m in height. Huge lava column, lava speleothems: stalactites, stalagmites, helictites, bridges, shelves, flowstone, balls, ropy lava. Gimnyeong 705 m S-shaped passage. Lava speleothems: shelves, lava falls, stalactites, cave corals, carbonate sands. Yongcheon 2,470 m Lava speleothems: Stalagmites, stalactites, rolls, terraces, shelves, droplets, wall and ceiling pockets, lake. Secondary features formed of leached calcite: soda straws, stalactites, stalagmites, columns, curtains, rimstone pools, cave corals, moonmilk, cave flowers, cave pearls. CLIMATE The island has a subtropical oceanic climate, moderated by the Tsushima current from the south, rising with altitude through warm temperate to subarctic. There are four distinct seasons. The average January temperature is 6.2 oC, the average August temperature is 27.2 oC, the coasts being the warmest, but the average annual temperature in the site is 11.7oC. Winters are short and relatively warm, with only 17 days of frost. On site rainfall averages 2,044mm and, rising with height, is greatest (2,766mm) on the southeastern slopes of Hallasan. Snow falls between November and May. Half the total precipitation falls in summer low-pressure storms, and spring is continuously drizzly, but long rainstorms are common in winter. Winds are strong especially from the northeast in winter. An average of 2.4 typhoons a year was recorded between 1940-1982, mostly during the late summer monsoon season.